/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.types.inference;

import org.apache.flink.annotation.Internal;
import org.apache.flink.util.Preconditions;

import java.util.Objects;
import java.util.Optional;

/**
 * Helper class for {@link ArgumentCount} with constant boundaries.
 *
 * <p>Note: All boundaries of this class are inclusive. All indices are 0-based.
 */
@Internal
public final class ConstantArgumentCount implements ArgumentCount {

    private static final int OPEN_INTERVAL = -1;

    private final int minCount;

    private final int maxCount;

    private ConstantArgumentCount(int minCount, int maxCount) {
        this.minCount = minCount;
        this.maxCount = maxCount;
    }

    public static ConstantArgumentCount of(int count) {
        Preconditions.checkArgument(count >= 0);
        return new ConstantArgumentCount(count, count);
    }

    public static ConstantArgumentCount between(int minCount, int maxCount) {
        Preconditions.checkArgument(minCount <= maxCount);
        Preconditions.checkArgument(minCount >= 0);
        return new ConstantArgumentCount(minCount, maxCount);
    }

    public static ConstantArgumentCount from(int minCount) {
        Preconditions.checkArgument(minCount >= 0);
        return new ConstantArgumentCount(minCount, OPEN_INTERVAL);
    }

    public static ConstantArgumentCount to(int maxCount) {
        Preconditions.checkArgument(maxCount >= 0);
        return new ConstantArgumentCount(0, maxCount);
    }

    public static ConstantArgumentCount any() {
        return new ConstantArgumentCount(0, OPEN_INTERVAL);
    }

    @Override
    public boolean isValidCount(int count) {
        return count >= minCount && (maxCount == OPEN_INTERVAL || count <= maxCount);
    }

    @Override
    public Optional<Integer> getMinCount() {
        return Optional.of(minCount);
    }

    @Override
    public Optional<Integer> getMaxCount() {
        if (maxCount == OPEN_INTERVAL) {
            return Optional.empty();
        }
        return Optional.of(maxCount);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        ConstantArgumentCount that = (ConstantArgumentCount) o;
        return minCount == that.minCount && maxCount == that.maxCount;
    }

    @Override
    public int hashCode() {
        return Objects.hash(minCount, maxCount);
    }
}
